Great Blue Lobelia - Lobelia syphilitica

Features:  Clusters of blue-violet flowers may last up to two months in late summer. They are pollinated by bumblebees and also attract butterflies and other insects. 

Light: Partial sun to partial shade

Soil: Wet to moist; good for the rain garden

Height: 1-4 feet

Blooms: August to September

See more information and photos at Illinois Wildflowers and USDA Plants Database